Method and apparatus for coating a decorative workpiece

ABSTRACT

A method and apparatus is provided for applying a plaster-like coating material to the decorative exposed surface of a preform workpiece. The apparatus comprises; means for mechanically advancing a workpiece along the apparatus along a straight horizontal axis over a non-continuous surface; means for engaging the bottom portion of a workpiece to constrain lateral and vertical movement as the workpiece passes along the apparatus; and means for applying a desired thickness of plaster-like coating material to a decorative surface of an advancing workpiece. Both the method and apparatus provide on a consistent basis, a smooth coating with a controlled thickness tightly bonded to the entire exposed decorative surface of a workpiece. The method and apparatus provide a simple, efficient, cost effective and reliable means for applying a plaster-like coating to the exposed decorative surface of a workpiece for use on a commercial scale in the construction industry.

RELATED APPLICATIONS

[0001] This application is a Divisional patent application of Serial No.09/725,395 which is a Divisional Continuation-In-Part of U.S.application Ser. No. 09/137,593 filed Aug. 21, 1998 which is aContinuation-In-Part of U.S. application Ser. No. 08/942,587 filed Oct.2, 1997.

FIELD OF THE INVENTION

[0002] This invention relates to decorative mouldings and moreparticularly to a method and apparatus for coating preformed workpieceshaving decorative surfaces.

BACKGROUND OF THE INVENTION

[0003] Preformed workpieces such as decorative mouldings are widely usedin the construction industry. Such mouldings are designed to be mountedagainst exterior or interior walls for providing architectural featureson building structures in sectors such as residential, industrial,commercial and institutional buildings. The exposed surface of themoulding is usually decorative and as such, has an irregular surface incross-section and continuous in the longitudinal direction. Mouldingscan be fabricated from several materials including wood, plaster andexpanded polystyrene (EPS). EPS mouldings are particularly attractive touse because of their relatively light weight and ease of fabrication. Inorder that the moulding be both attractive and durable, mouldingsubstrates or workpieces are typically coated with various coatingmaterials to provide an attractive finish to the product. Traditionally,mouldings have been coated by hand after the EPS moulding is secured tothe exterior of the structure. This involved applying with hand tools, alayer of base coat to the moulding and then embedding a fiberglass meshonto the moulding and allowing it to dry. A layer of stucco or specialpaint as a finish coat is usually subsequently applied to the basecoated moulding after the moulding is installed. This method is verylabor intensive and consequently, very slow and expensive. Often times,the quality of the applied base coating is not consistent due to poorworkmanship. This results in a coating of uneven thickness whicheventually cracks and does not look very attractive.

[0004] More recently, various types of automated equipment have beendesigned to apply coatings to different types of workpieces. Forexample, U.S. Pat. No. 5,514,417 discloses a method and apparatus forcoating a molded fibrous workpiece with a foam material. In this methodand apparatus, the workpiece is passed through a foam bath within acoating chamber. To ensure a good coating of the workpiece, the foammaterial is spread over the entire exterior surface of the workpieceusing wipers within the coating bath.

[0005] Canadian patent 2,184,205 discloses a method and apparatus forapplying a coating material onto the surface of a decorative workpiece.In this method, the workpiece is slid through a bath of coating materialcontained within a coating chamber where the coating material is appliedsimply under the weight of the material. The workpiece is slidinglyadvanced on a continuous flat platform by a set of guide rollersabutting both sides of the workpiece both before and after passingthrough the coating bath while simultaneously shielding the bottomsurface of the workpiece. This method and apparatus does provide acoating on the decorative surface of the workpiece, however, theresultant coating may be inconsistent with respect to its thickness.This is partly due to the fact that the workpiece moves and slides abouton the platform as it is being guided into the coating chamber. This isalso true when the workpiece exits the coating bath, as lateral,horizontal and vertical movement will result in varying thicknesses ofcoating material being applied to the surface of the workpiece as itexits the coating bath. Furthermore, once in the coating chamber, thecoating material may not be evenly distributed onto the intricate curvespresent on the exterior design of the workpiece. The coating materialcan bubble on the surface of the workpiece due to having the workpiecepass through a bath of thick, viscous coating material at varying speedswhich results in different rates of shear of the material at the bathexit. Consequently, parts of the workpiece will not be coated adequatelyor not at all. Once the workpiece exits the bath, it may not be allowedto dry sufficiently before the guide rollers, continue to advance itforward and thus contact the wet coated workpiece and possibly damageits coating. Also, it is required that the coated mouldings air dry forat least 24 hours.

[0006] There is therefore a need to develop a novel method and apparatusfor coating decorative workpieces used widely in various constructionsectors, in a consistent, simple, efficient manner such to provide asmooth durable coating distributed in a controlled manner to desiredexposed decorative surfaces of a workpiece. There is also a need toprovide a finished coated workpiece which has a smooth, exterior coatingfinish which is aesthetically pleasing as well as very durable and thusresistant to damage.

SUMMARY OF THE INVENTION

[0007] In accordance with the present invention there is provided amethod and apparatus for applying a coating material to the decorativeexposed surface of a preform workpiece. Both the method and apparatusprovide on a consistent basis, a smooth durable coating with acontrolled desired thickness to the entire exposed decorative surface ofa workpiece. The coating as applied to the surface of the workpiece istightly bonded thereto such that it cannot be removed therefrom withoutcausing damage to the workpiece itself. The coating material is aplaster-like coating material and can be selected from cement based andpolymeric based materials as is known to those skilled in the art.

[0008] The method and apparatus avoid the problems of having air bubblesin the finished coating, delamination of the coating from the workpiece,the appearance of cracks in the coating or an uneven thickness ofcoating material left on the coated workpiece. The method and apparatusare relatively simple, efficient and cost effective and reliably on aconsistent basis provide a means for applying a plaster-like coating tothe exposed decorative surface of a workpiece on a commercial scale foruse in the construction industry.

[0009] According to an aspect of the present invention there is providedan apparatus for applying a coating material to exposed surfaces of apreform workpiece having a decorative exposed surface and a bottomportion, said apparatus comprising:

[0010] means for mechanically advancing a workpiece along said apparatusalong a straight horizontal axis over a non-continuous surface;

[0011] means for engaging the bottom portion of a workpiece to constrainlateral and vertical movement as the workpiece passes along saidapparatus; and

[0012] means for applying a desired thickness of coating material to adecorative surface of an advancing workpiece.

[0013] Preferably, the decorative preform workpiece has a mesh laminatedto its decorative surface prior to being advanced through a coatingchamber.

[0014] In one embodiment of the invention, the coating means is alsoadapted to apply a coating to the bottom outside edges of the bottomportion of the workpiece.

[0015] According to a further aspect of the invention is a method forapplying a coating material to exposed surfaces of a preform workpiecehaving a decorative exposed surface and a bottom portion, said methodcomprising the steps of:

[0016] continuously advancing said workpiece in a straight horizontalaxis via engagement of said workpiece by its bottom portion to preventlateral and vertical movement of said workpiece as it is being advanced;

[0017] applying a plaster-like coating material to the exposed irregulardecorative surface of the advanced workpiece; and

[0018] advancing the coated workpiece through a die opening closelyconforming to the cross-sectional profile of the workpiece, wherein thecross sectional size of the die opening relative to the cross sectionalsize of the workpiece determines the thickness of the plaster-likecoating material left remaining on the decorative surface of the coatedworkpiece.

[0019] According to yet a further aspect of the invention is a methodfor applying a coating material to exposed surfaces of a preformworkpiece having a decorative exposed surface and a bottom portion, saidmethod comprising the steps of:

[0020] providing a workpiece having a thin mesh laminated to its entiredecorative surface and to the outer bottom edges of the bottom portionof the workpiece;

[0021] continuously advancing said workpiece in a straight horizontalaxis wherein said workpiece is engaged via its bottom portion to preventlateral and vertical movement of said advancing workpiece;

[0022] applying a coating material to the exposed irregular decorativesurface of the workpiece; and

[0023] advancing the coated workpiece through a die opening closelyconforming to the cross-sectional profile of the workpiece, wherein thecross sectional size of the die opening relative to the cross sectionalsize of the workpiece determines and controls the thickness of theplaster-like coating material left remaining on the decorative surfaceof the coated workpiece.

[0024] According to still a further aspect of the invention is a methodfor bonding a coating material to desired exposed surfaces of a preformworkpiece having a decorative exposed surface and a bottom portion, saidmethod comprising;

[0025] anchoring a thin mesh to the entire decorative surface of theworkpiece and to the outer bottom edges of the bottom portion of theworkpiece; and

[0026] applying a coating material under pressure to said anchored meshto bond said mesh to said decorative exposed surface and to the outerbottom edges of the bottom portion of the workpiece, wherein saidbonding creates a finished smooth protective coating on said workpiece.

[0027] Preferably, the bonding method is a two step process wherein thefirst step applies a coat of coating material which completely submergesthe mesh and anchors it into the surface of the workpiece. The secondstep of the process provides a top coat of coating material whichprovides a smooth attractive durable finish.

[0028] Typically, the first step provides a thicker coating of coatingmaterial and the second step provides a thinner coating materialcompared to the first step. If desired, additional thin layers ofcoating material can be applied to a coated workpiece.

[0029] According to yet another aspect of the invention is a preformworkpiece comprising;

[0030] an elongate body having an exposed decorative surface and asubstantially flat bottom portion; and

[0031] means for facilitating the adherence of a coating material to theexposed decorative surface of said workpiece.

[0032] According to yet a further aspect of the present invention is acoated workpiece comprising;

[0033] a preformed workpiece having a decorative exposed surface with aplurality of spaced apart surface grooves orientated longitudinallyalong the length of said workpiece and a substantially flat bottomportion;

[0034] a mesh laminated to the exposed surface and partially aboutbottom outside edges of bottom portion of said workpiece; and

[0035] at least one layer of a coating material bonding said mesh to theexposed decorative surface and to bottom outside edges of the bottomportion of said workpiece, wherein the coating material impregnates themesh and anchors said mesh within said surface grooves within saiddecorative exposed surface such that the mesh and coating material arefirmly bonded to the decorative surface of the workpiece. In oneembodiment a thin layer of coating material may also impregnate andanchor the mesh located about the bottom outside edges of the bottomportion of said workpiece.

[0036] Both the preform workpiece and the coated workpiece mayadditionally have a means for mounting such workpieces to a desiredsurface located in the flat bottom portion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] A detailed description of the preferred embodiments are providedherein below with reference to the following drawings in which:

[0038]FIG. 1 is a perspective view showing the apparatus in accordancewith a first embodiment of the present invention;

[0039]FIG. 2 is a cross-sectional view through lines A-A of FIG. 1showing a workpiece inside a coating chamber;

[0040]FIG. 3 is a cross sectional view through lines B-B of FIG. 1showing a workpiece inside the coating chamber;

[0041]FIG. 4 is an enlarged view of segment A in FIG. 3;

[0042]FIG. 5 is an enlarged top plan view of the preferred mesh for usein laminating the decorative surfaces of the workpiece in accordancewith the present invention;

[0043]FIG. 6 is a cross-sectional view through lines A-A of FIG. 1showing a different embodiment of the workpiece and apparatus, theworkpiece having a dovetail channel and surface grooves and theapparatus having a correspondingly fitting rail for the dovetailchannel;

[0044]FIG. 7 is an enlarged view of segment B in FIG. 6;

[0045]FIG. 8 is a cross-sectional perspective view of the workpiece ofFIG. 6 before coating showing its dovetail channel and surface grooves;

[0046]FIG. 9 is a cross-sectional perspective view of the workpiece ofFIG. 8 having a mesh laminated to its exposed surfaces, prior to beingcoated;

[0047]FIG. 10 is a perspective view showing an apparatus in accordancewith another embodiment of the present invention;

[0048]FIG. 11 is a side elevational view of the apparatus of FIG. 10;

[0049]FIG. 12 is an enlarged side elevational view of segment C in FIG.11;

[0050]FIG. 13 is an enlarged perspective view of the coating chamber ofthe apparatus of FIG. 10;

[0051]FIG. 14 is an enlarged front cross-sectional view of the coatingchamber of FIG. 13;

[0052]FIG. 15 is an enlarged side cross-sectional view of the coatingchamber of FIG. 13;

[0053]FIG. 16 is a perspective view of the die plates of the coatingchamber;

[0054]FIG. 17A is a perspective enlarged view showing the coatingchamber of apparatus of FIG. 13 in accordance with another embodiment ofthe present invention;

[0055]FIG. 17B is an enlarged cross-sectional view of the dams of thecoating chamber of FIG. 17A;

[0056]FIG. 18 is an enlarged side cross-sectional view of a workpiecemoving through the coating chamber of FIG. 13 and receiving a firstcoating;

[0057]FIG. 19 is an enlarged side cross-sectional view of a coatedworkpiece moving a second time through the coating chamber of FIG. 13 toreceive a second coating;

[0058]FIG. 20 is a cross-sectional perspective view of a finished coatedworkpiece having first and second coating layers, in accordance with amethod of the present invention;

[0059]FIG. 21A is a cross-sectional view of a workpiece having a firstanchoring coating;

[0060]FIG. 21B is an enlarged view of segment D of FIG. 20A;

[0061]FIG. 22A is a cross-sectional view of the finished workpiece ofFIG. 19;

[0062]FIG. 22B is an enlarged view of segment E of FIG. 21A;

[0063]FIG. 23 is a further embodiment of the workpiece of FIG. 20; and

[0064]FIG. 24 is a perspective view showing a mesh applying apparatuswhich can be used with the different apparatus embodiments of thepresent invention.

[0065] In the drawings, preferred embodiments of the invention areillustrated by way of example. It is to be expressly understood that thedescription and drawings are only for the purpose of illustration and asan aid to understanding, and are not intended as a definition of thelimits of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] Referring to FIG. 1, there is illustrated a first embodiment ofthe apparatus 10 of the present invention in which a workpiece 12 iscoated. The workpiece 12, better seen in FIG. 2, comprises a core 14having an exterior decorative surface 16 which may be irregular incross-section, but consistent along the workpiece length. A bottomportion 18 is provided on the workpiece which may be flat. A mesh 20covers the entire decorative surface 16 of the workpiece. The decorativesurface provides a unique cross-sectional profile 22 for the workpiece.The workpiece 12 is designed to be mounted on an exterior wall via itsbottom portion 18 being secured or mounted on a mounting surface and inthis manner the irregular decorative surface 16 is clearly visible.

[0067] Referring back to FIG. 1, the apparatus 10 comprises a platform24 which supports a conveyor system for advancing the workpiece in ahorizontal axis through the apparatus. The conveyor system consists of apair of adjacent conveyor belts 26, 28 onto which the workpiece 12rests. The conveyor belts 26, 28 have several spikes 30 which protrudeupwardly and into the bottom portion 18 of the workpiece 12 to drive theworkpiece directly through the apparatus while minimizing lateralmovement of the workpiece 12 as it is being advanced through theapparatus. The workpiece 12 also has a channel 32 in its bottom portion18 which is engaged by a corresponding rail 34 located in the middle ofthe platform 24 and separating the conveyor belts 26, 28. Thisengagement acts to constrain lateral and vertical movement of theworkpiece as it advances through the apparatus. This also ensuresaccurate positioning of the workpiece as it is being advanced throughthe coating station of the apparatus to ensure that a controlled amountof coating is applied. The rail 34 is provided down the entirehorizontal axis and length of the apparatus. Guides 29 are positioned oneither side of the platform 24, and function to line up incominguncoated workpieces immediately preceding a workpieces being coated.

[0068] A rotating tension wheel 38 is biased against the top decorativesurface of the workpiece. This wheel rotates along the decorativesurface of the workpiece as it is advancing through the apparatusupstream of the coating chamber and helps to restrain vertical movementof the advancing workpiece. The tension wheel is mounted to the platformby an arm member 40 which is spring loaded via a spring 42 to a verticalsupport 44. It is understood by those skilled in the art that more thanone tension wheel can be used, depending on the width of the workpiece.The workpiece 12 is advanced into an interchangeable coating chamber 46via an inlet 48 closely conforming to the cross-sectional profile 16 ofthe workpiece through which the workpiece is advanced. The inlet is justlarge enough to allow the workpiece to enter the coating chamber butwill not allow for the coating material to escape. Several conduits 50enter and open into the chamber 46 through which a plaster like coatingmaterial 52 is fed preferably under pressure from a reservoir 54. Thepressurization of the coating material ensures that the coating materialis applied to all of the intricate surfaces of the workpiece as it isbeing advanced through the coating chamber 46. This also ensures thatthe coating material not only penetrates through the mesh andinfiltrates into surface crevices of the workpiece, but also that themesh is impregnated by the coating material and is thereby adhered tothe workpiece surface by the coating material.

[0069] Preferably, the conduits 50 enter and open into the coatingchamber 46 at both the top and sides of the chamber to ensure thatcoating material 52 is constantly supplied to all regions of the chamberand is thereby applied to the entire decorative surface. In accordancewith a preferred embodiment, the application of the coating materialunder pressure results in an even application of the coating materialand less buildup of material in the chamber.

[0070] As seen in FIG. 2, the workpiece 12 must move through the coatingchamber 46 in a straight path in order that the now coated workpiece 54can exit the coating chamber 46 via a die opening 56 closely conformingto the cross sectional profile of the coated workpiece in the properorientation. This die opening 56 is slightly larger than the inlet 46 ofthe coating chamber so that a desired controlled thickness of coatingmaterial is applied under pressure on the decorative surface of theworkpiece as it exits the coating chamber.

[0071] It is understood by those skilled in the art, that while the dieopening 56 defined by die plate edge 57 conforms to the cross sectionalprofile of the workpiece, the size and shape of the die opening can varyin order to provide a controlled thickness of coating material inselected regions of the decorative surface. The die shape helps toprovide the controlled thickness of coating material on the decorativesurface of a workpiece. For example, the spacing of the die edge 57 fromthe workpiece surface may be greater at raised areas 55 of a decorativesurface to provide a thicker coating in that region to ensure completecoating on the complex curves of the raised areas. It may also bedesired to provide a thicker layer of coating material on flat portions59 of the decorative surface of the workpiece where the workpiece willbe adhered to a wall via a fastening means extending through the flatareas such as by use of retention screws. The thicker coating at 59, assuch will provide a more secure fastening of the coated workpiece to awall.

[0072] The resulting coated workpiece 54 is continually advanced throughthe apparatus engaged via its channel to the rail 34 before beingremoved from the apparatus. It is preferred that the coated workpiece aspassed once through the apparatus be placed in a curing chamber for 8-12hours after which it can be shipped for sale and use. As is best seen inFIG. 3, the coating chamber has angled walls 47 in order to create ashear edge at the point the coated workpiece leaves the chamber with alayer of coating material thereon. This forces coating material into asmaller cross-section. Consequently, the shearing of the coatingmaterial onto the surface leaves a smoother more desired finish.

[0073] The engagement of the workpiece with the platform of theapparatus via the rail 34 and the spikes 30 together act to drive theworkpiece into and out of the coating chamber in the straightest andmost stable manner possible in order to consistently provide acontrolled even thickness of coating onto the exposed surface of thedecorative workpiece as it enters and exits the coating chamber.

[0074] The workpiece 12 can be fabricated to have several differentstyles of decorative surfaces by the provision of differentcross-sectional profiles 22. It is understood that the workpiece may beformed in a variety of ways depending primarily on the materials ofconstruction. It may be milled, extruded or otherwise shaped. Preferablyif the material is expanded polystyrene (EPS), a block of EPS is cutwith a hot wire system to cut the decorative surface outline and therebyprovide an elongate workpiece ready for coating. For example, theworkpiece can be cut into 2.2 cm×11 cm (11″×5″) plates, 6.6 cm×13.2 cm(3″×6∝1) cornice mouldings, 2.2 cm×13.2 cm (1″×6″) window and door trimand 2.2 cm×17.6 cm (1″×8″) wall trim. The workpiece can also be cut intovarious sizes to be later adhered together to form columns. The lengthof the workpiece may also vary depending on the final use. Typicallengths of workpieces are approximately 2.5 m to 5 m long.

[0075] The workpiece used in the present method can be made of anysuitable light weight material including wood and plastic. The preferredmaterial is made of expanded polystyrene (EPS) or polyurethane. Thephrase “decorative surface” as used herein refers to the portion of theworkpiece that is exposed and readily seen when the workpiece is mountedto a surface, usually a wall. The decorative surface can be of anyintricate shape or design.

[0076] It is understood by those skilled in the art that the method ofthe present invention can be used on workpieces of varying crosssectional sizes and designs as well as lengths. This may be accommodatedby having a coating chamber with varying sizes and configurations ofinlet and exit die opening. The coating chamber, itself, can befabricated in several sizes dictated by the size of the workpiece andthe size of the profile of the workpiece. The size of the exit dieopening determines the thickness of coating material and shape ofcoating material left layered on the workpiece as it exits the coatingchamber. The thickness of coating material can vary from about 2-4 mmdue to the provision of an exit die edge 57 being spaced a correspondingextent away from the decorative surface of the workpiece. However, it isunderstood by those skilled in the art that the thickness of coatingmaterial may also vary according to the needs of the customers. It isalso understood, that the workpiece can be coated more than once byadvancing an already coated workpiece again through the coating chamberusing a die opening larger than the first pass through the coatingchamber.

[0077] Several different types of mesh can be used to laminate theworkpiece prior to being coated with coating material. The mesh servesnot only to reinforce the surface of the workpiece, but also helps tobind the coating to the workpiece surface to provide a hard, protectiveand attractive surface. Preferably, the mesh used on the decorativesurface is made from a fiberglass having a protective coating. The meshalso has a tacky surface which is adhered to the decorative surface ofthe workpiece. In accordance with the preferred embodiment of thecoating material being applied under pressure, this results in the meshbeing impregnated with the coating material which then cures to providea hardened surface.

[0078] The mesh is applied to the decorative surface as well as wrapsaround just underneath the bottom flat outside edges of the workpiece toensure that all surfaces and edges are properly coated and the meshembedded. This also helps to prevent the mesh from unraveling at thebottom edges of the workpiece. The bottom portion of the workpieceremains uncoated. The provision of the mesh wrapping around the bottomflat edges of the workpiece also provides a means for the mounting ofthe coated workpiece to a vertical surface. To mount the coatedworkpiece, the wrapped around mesh portions are pulled away from theflat bottom portion of the workpiece and spread out vertically away fromthe body of the workpiece. The coated workpiece is then placed against avertical surface and permanently mounted to a wall with the applicationof an adhesive, nails or screws to the vertically extended mesh. Withthe coating material reinforcing the mesh to the bottom edges of theworkpiece, this provides a more secure fashion to mount the coatedworkpiece to a vertical surface such as a wall.

[0079] As seen in FIG. 4, the mesh may be specifically engineered tocomprise thick strands of glassfibre 20A interspersed with 4 to 6thinner strands 20B of glassfibre. While the mesh is shown to comprise acriss cross pattern of mesh, it is also desirable to use a mesh whichincludes a longitudinal pattern of fibreglass strands with differingthicknesses. The coating material 52, is shown to completely submergethe mesh 20. A preferred mesh for use in the present invention is shownin FIG. 5. This mesh has wide, flat longitudinal strands 20A withcrisscrossing narrower, but thicker strands 20B. As laminated onto thesurface of the workpiece, the wider strands are supported above thenarrow strands and provide a space for the coating material toimpregnate the mesh. Thus this specifically engineered mesh allows forthe coating material to flow underneath and embed the raised thinnerstrands 20B in the coating material, and into the intricate surface ofthe workpiece, such as in crevices, and in this manner, better adherethe mesh and the coating material to the surface of the workpiece.

[0080] It is understood by those skilled in the art that severaldifferent types of coating materials can be used in the method and withthe apparatus of the present invention including cement-based, polymericbased and the like so long as the coating cures to a fine smooth finishthat is visually appealing. A preferred type of coating material for usein the present invention is a polymeric based coating that is resilientwhen cured.

[0081] Another embodiment of the present invention is shown in FIGS. 6through 9 and is designed to further enhance the anchoring of the mesh20 and the bonding of the coating to the preform workpiece surface. Inthis preferred embodiment, the workpiece 65 is fabricated to havemultiple grooves or channels 66 along its exposed decorative surface 67that may run along the entire length of the workpiece 65 as clearlyshown in FIGS. 8 and 9. Such grooves 66 are preferably spaced apartapproximately ½ inch along the exposed surface and are approximately⅛^(th) inch deep. Alternatively, the grooves can be discontinuous andalternatively positioned or staggered on the surface of the workpiece.These grooves perform the function of assisting the coating material totightly anchor the mesh 20 to the workpiece. As the coating material isapplied under pressure to the surface of the mesh laminated workpiece(seen in FIG. 6), it flows throughout the mesh and into the grooves. Asthe coating cures with the mesh embedded therein and the coating is inturn embedded in the grooves, this fixes or secures the mesh on thesurface of the workpiece forming a tight bond illustrated in FIG. 7. Thecoating material 52 impregnates the surface grooves and impregnatesthrough the mesh 20 and into the grooves 66 and intricate crevices ofthe surface 16 of the workpiece. This impregnation achieves a very tightbond such that the cured coating cannot be easily chipped or peeled awayfrom the workpiece. To demonstrate the strength of the bond between thecoating and the workpiece itself, any attempt to strip the coating froma styrofoam workpiece would tear away the embedded mesh and remove asurface layer of the styrofoam (EPS) preform thus substantially damagingit. This tight bond of the coating material to the workpiece surface istruly unique and is not present on any coated workpiece currentlyavailable on the market. This is particularly advantageous where thecoated workpieces may be exposed to potential accidental damage at aconstruction site.

[0082] Prior art coating methods provide a laminated coating which canbe easily delaminated by pulling off the mesh and cured coating withoutappreciably tearing away the surface of the workpiece. In this sense,the coating of the prior art is merely layered onto the workpiecesurface. In contrast, in the method of the present invention, theprovision of surface workpiece grooves together with the specializedmesh and the novel coating apparatus, results in a coating that doesn'tmerely layer on the surface of the workpiece, but actually bonds andcements into the irregular surface of the workpiece. The mesh and curedcoating are caused to embed into the granular matrix of the styrofoamworkpiece. Any attempt to strip the mesh and cured coating from theworkpiece, rips apart the individual beads of the styrofoam and thus theconstruction of the workpiece body. This is not seen with any coatedworkpiece of the prior art. Due to this very adherent and bondedcoating, the coated workpiece can withstand a great deal of wear andtear without sustaining any substantial damage or delamination andtherefore is easy to install as it requires no special care orattention.

[0083] The provision of the grooves spaced along the entire length ofthe workpiece creates a novel type of moulded coated workpiece whichcannot be easily delaminated yet retains its lightweight and flexiblecharacteristics. It is understood by those skilled in the art, that thenumber, length and placement of grooves and the size of groove on thesurface of the workpiece may vary depending on the size of the workpieceto be coated. It is also understood that rather than continuous ordiscontinuous grooves provided on the decorative surface of theworkpiece, small holes or indents can be punched evenly or randomlyspaced on the surface of the decorative workpiece to help anchor themesh with coating material to the surface of the workpiece. The type orshape of groove, hole or indent is not limiting so long as coatingmaterial can be forced into such in order to bond the mesh tightly tothe decorative surface. It is also appreciated that grooves, holes orindents may be mechanically placed on the surface of the apparatus at astation upstream of the coating chamber and upstream or downstream of amesh laminating location.

[0084] As also seen in FIGS. 6, 8 and 9 in this preferred embodiment ofthe invention, the workpiece 65 has a dovetail channel 68 to engage withthe corresponding shaped rail 34 located in the middle of the platform24. This channel runs preferably along the middle of flat bottom portion69 of the workpiece and along the entire length of its longitudinalaxis. The design of the dovetail channel helps to restrain both lateraland vertical movement of the entire length of workpiece as it advancesand is driven forward on the conveyor system supported within thenoncontinuous platform and through the coating chamber to ensure an eventhickness of coating material is applied to the surface of theworkpiece. The rail extends along substantially the entire length of thenon continuous platform including within the coating chamber and ontothe downstream end of the platform. In this manner the workpiece is wellrestrained to minimize erroneous movement in order to provide an evenand consistent coating onto the workpiece surface.

[0085] While the preferred shape of rail is shown to be dovetailed, itis understood by those skilled in the art that the rail andcorresponding channel located within the bottom portion of the workpiececan be of varying configurations having some degree of undercut in orderthat the engagement of both the rail and channel of the workpiece actsto hold the workpiece in place in a horizontal axis when advanced alongthe apparatus. For example, the rail and correspondingly fitted channelcan be T-shaped.

[0086] In this preferred embodiment of the invention, the coatingchamber has locating slots 70, 72 as shown in FIG. 6, adjacent to and oneither side of the die opening which engage with corresponding spacedcentering projections or pins 74, 76 located on the platform 24 of theapparatus. These slots and projections are spaced to ensure that therail 34 is preferably located at the exact desired position in the dieopening 56. It is the rail that controls the proper positioning of theworkpiece as it is being advanced through the die opening. Preferably,the rail is centrally positioned in the die opening as indicated bycentre line 35. Thus the provision of locating slots on the sides of thedie opening with centering projections located on the platform ensuresthat the workpiece advances in the correct orientation into and throughthe coating chamber and thus be properly and evenly coated. It isunderstood that more than one rail can be used in the method andapparatus of the present invention to properly advance a workpiecethrough the apparatus. This is especially true for larger, widerworkpieces for which the additional dovetail grooves and theirengagement with additional rails would provide for more stability duringadvancement of a large, wide workpiece. The locating slots and centeringprojections thus provide an easy and quick method to ensure that therails are properly positioned within the die opening and for the entireapparatus.

[0087] It is understood by those skilled in the art that the apparatusof the present invention may include a continuous process whereby theworkpiece is first coated with mesh and then directly with coatingmaterial prior to curing. Alternatively, the apparatus may comprise oneor more stations including curing and mesh laminating stations wheredesired. The distance between various stations may also vary.

[0088] In the method of the present invention, the workpiece having meshadhered to its surface, is mounted via its channel onto thecorresponding rail of the apparatus. The workpiece is mechanicallyadvanced over the non-continuous surface into the coating chamber viathe inlet. Inside the coating chamber, coating material is fed underpressure in order to infiltrate and impregnate the intricate surface ofthe workpiece and the overlying mesh as it travels through the coatingchamber. As the workpiece continues to be mechanically advanced, itexits the coating chamber through an exit die having a cross sectionalprofile which determines the desired thickness of coating to be applied.As such, the die profile may correspond essentially to the crosssectional profile of the workpiece or may be different in certainsections if it desired to have a thicker coating in certain regions ofthe decorative surface. The exit die may be slightly greater in crosssectional profile as compared to the workpiece in order to leave adesired thickness of coating material on the workpiece as it exits thechamber. The coated workpiece is then cured in a dehydration chamber inwhich the environmental factors are controlled to ensure an even andrapid curing of the coating material onto the workpiece. The curedworkpiece is then ready for use. Throughout the entire coating method,the bottom portion of the workpiece is not exposed to coating materialand therefore remains uncoated.

[0089] Another most preferred embodiment of the invention is illustratedin FIGS. 10 and 11 in which the apparatus is indicated as referencenumeral 100. In particular, a different coating chamber design is usedin this embodiment of the invention. In this embodiment of the apparatusit is preferred to use a workpiece having a dovetail channel 168 locatedin the bottom portion 118 of the workpiece 112. The apparatus 100comprises a non-continuous platform 124 which supports two conveyorsystems 125 and 127. Conveyor system 125 is positioned upstream of acoating chamber 146 and the other conveyor system 127 is positioneddownstream of the coating chamber 146. The conveyor system 127positioned downstream of the coating chamber 146 may be set at adifferent speed from that of the first conveyor system 125 positionedupstream of the coating chamber 146. In this manner, the second conveyorsystem 127 helps to separate the coated workpieces as they exit thecoating chamber 146 which speeds up the entire coating process as theseparated coated workpieces can then be quickly moved into anenvironmentally controlled curing chamber.

[0090] Each conveyor system 125, 127 comprises a pair of adjacentconveyor belts 126, 128 onto which the workpiece 112 rests. The conveyorbelts have several spikes 130 which protrude upwardly above platform 124and into the bottom portion 118 of the workpiece 112 which act primarilyto drive the workpiece along and through the apparatus but also help toprevent lateral movement of the workpiece 112 as it is being advancedand driven through the apparatus. This is particularly exemplified inFIG. 12. The preferred workpiece 112 for use in this embodimentpreferably has a dovetail channel 168 in its bottom portion 118 (shownin FIGS. 8 and 9) which engages with a corresponding dovetail rail 134located in the middle of the non-continuous platform 124 and separatingthe conveyor belts 126, 128. This engagement in addition to the spikedconveyor belts acts to guide movement of the workpiece through theapparatus while constraining lateral and vertical movement of theworkpiece as it being driven and advanced through the apparatus. In thismanner, additional restraining components such as a rotating tensionwheel are not required. The dovetail channel 168 and correspondingdovetail rail 134 also ensure accurate positioning of the workpiece asit passes through the apparatus. In addition, the rail systemfacilitates passing of the coated preform over an open space 131,downstream of the coating device 146. The open space has rail 134passing over the open space 131. Beneath the open space 131 may be adrip pan to collect any excess coating which may drop from the coatingchamber. The open space 131 has adjustable rails 133 to engage selectedportions of preform bottom after it immediately exits the coatingchamber 146.

[0091] While the spiked conveyor belts are shown to be positioned toengage the bottom portion of the workpiece to drive the workpiecethrough the apparatus, it is also understood that such spiked conveyorbelts can be engineered to engage the workpieces at the sides or theexposed decorative surface to drive the workpiece straight through theapparatus. The spiked conveyor belts can be made to extend any desiredlength of the non-continuous platform upstream and downstream of thecoating chamber. Spiked conveyer systems may also be modified tocomprise any means to “hold” or “anchor” the bottom portion of theworkpiece as it is being advanced via the conveyor belts. Such means mayalso include providing a tacky adhering surface for the conveyor beltsor alternatively suction means.

[0092] The workpiece is advanced into an interchangeable coating chamber146 via an inlet 148 which may closely conform to the cross-sectionalprofile of the workpiece through which the workpiece is advanced. Theinlet is just large enough to allow the workpiece to enter the coatingchamber but minimizes the escape of pressurized coating materialtherefrom. A conduit 150 enters and opens into the top of the coatingchamber 146 through which the coating material is fed under pressurefrom a reservoir.

[0093] As better seen in FIG. 13, the dovetail rail 134 is continuousthrough the coating chamber 146 and it engages the bottom portion of theworkpiece along the entire length of the discontinuous apparatussurface. A removable hatch 169 is provided at the top of the coatingchamber. This hatch can be removed in order to gain entry into thecoating chamber during the coating process and agitate the coatingmaterial. Defining the bottom of the coating chamber is a trough 170 inwhich are located spaced apart dams 172 slidingly engaged on spacedapart rails 174. As seen in FIG. 14 the dams 172 are movable in order beproperly positioned and substantially aligned with the bottom outsideedges 176 of the bottom portion 116 of the advancing workpiece. Therails 174 are fastened to the bottom of the trough 170 by bolts 178.This arrangement prevents the bottom portion of workpiece being coatedin general. Surprisingly, this also provides on a consistent basis acontrolled application of a very thin, even coating of the coatingmaterial only to the bottom outside edges 176 of the bottom of theworkpiece 118 which surprisingly provides a more durable coating finishto the workpiece. This lip of coating material helps to bond and sealthe mesh about the outside bottom edges 176 of the bottom portion of theworkpiece 118 so it is virtually impossible to remove the coatingmaterial from the workpiece without the workpiece itself sustaining agreat deal of damage. The provision of a trough 170 and moveable dams172 functions specifically to allow for varying widths of workpieces tobe advanced through the coating chamber and obtain an even layer ofcoating material on the decorative surface while simultaneously applyinga controlled amount of coating material to the outside bottom edges 176of the bottom portion 116 of the workpiece on a consistent basis. Thedams 172 in particular help to provide an even pressure of coatingmaterial on the sides of the workpiece resulting in a cleaner,consistent finish on the bottom outside edge 176 of the bottom portionof the workpiece. Coating material is not applied to the entire bottomportion of the workpiece even though the bottom surface of the workpieceis not shielded from the coating material by the platform of theapparatus. To reiterate, this thin coating is important to better anchorthe mesh to the surface of the workpiece in particular, about its bottomoutside edges, such that the mesh is tightly anchored and very difficultto remove from the surface of the workpiece without causing substantialdamage to the workpiece. This creates a better durable coating finish onthe workpiece.

[0094] A sealant can also be used in conjunction with the dams in orderto help maintain the seal about the dams and thus pressurization of thecoating material within the coating chamber. A suitable sealant can be atype of putty or alternatively, a rubberized gasket.

[0095]FIG. 15 shows that the trough 170 defines the bottom portion ofthe coating chamber 146 over which the workpiece is advanced. Thisfigure also shows the angled position of the die opening 157 and theinlet 159. The angling of the plates provides a trowelling effect at theoutlet die to smooth out the coating as it exits the die. The angling ofthe inlet and outlet plates of about 5 0 from vertical provides inaccordance with this preferred embodiment an exceptionally smooth finishdue to the enhanced trowelling action. As seen in FIG. 16, the dieopening 157 and the inlet 159 are essentially interchangeable plateswhich are removable from the coating chamber by releasing bolts 171which clamp edges of the plates in clamping channel 173 and 175. Thelocating slots 170, 172 are positioned within the die opening and theinlet plates.

[0096] A further embodiment of the coating chamber of FIG. 13 is shownin FIG. 17A. In this aspect, the spaced apart adjustable dams 172 arepreferably constructed of a steel or like material and have a lip plate173 such that the bottom outside edges 176 of the bottom portion 116 ofthe advancing workpiece are better aligned within the coating chamber.The lip plate 173 additionally provides an edge 175 for the bottomportion 116 of the workpiece to ride against which is better illustratedin FIG. 17B. This acts to better position the advancing workpiece withrespect to the center of the apparatus as the edges 175 act as anadditional interior guidance mechanism on either side of the advancingworkpiece. This embodiment of the coating chamber provides for a cleanerbottom portion 116 of the workpiece as there is essentially no seepageof coating material within the coating chamber under the bottom portionof the advancing workpiece. This negates the requirement for a sealantto be used in conjunction with the dams. In this aspect, the bottomportion of the coating workpiece has essentially minimal or no coatingmaterial. Also, in this embodiment the trough 170 is filled with waterto help keep the bottom portion of the workpiece clean. Lastly, in thisembodiment it is desired to provide pressurized coating material (about60 to 80 psi) with appropriate back pressure.

[0097] The embodiment of the apparatus shown in FIGS. 10 to 19 can beused to provide multiple layers of coating material on the exposeddesired surfaces of the workpieces. For example, in FIG. 18, a workpiece65 having a mesh 20 laminated thereon is shown being advanced throughthe coating chamber 146 wherein the cross sectional profile of the dieopening is greater than the cross sectional profile of the inlet thusleaving a first layer of coating material 177 on the mesh laminatedworkpiece. The first layer 177 is thick enough to submerge and embed themesh 20 onto the surface 67 of the workpiece including the surfacechannels. In FIG. 19, a workpiece 65 having a first layer 177 of coatingmaterial embedding the laminated mesh 20 thereon is shown to be advanceda second time through the coating chamber leaving a second top coat 179or finishing coat of coating material to the desired exposed areas ofthe decorative workpiece. It is appreciated that the plates 157 and 159may be interchanged in applying the first and second coats. Plate 157 ispositioned on the outlet side for the first coat with the plate 159 atthe inlet side. The plates are switched to apply the second coating. Itis preferred that two layers of coating material be applied to theexposed decorative surface of the workpiece.

[0098] In accordance with the embodiments of the apparatus shown in FIG.10, it is most preferred to use a two step method for making a coatedfinished decorative workpiece 180 as shown in FIG. 20. The first stepinvolves passing a mesh laminated workpiece through the apparatus andthe coating chamber along a straight horizontal axis. The workpiece isengaged with the rod of the platform of the apparatus via its dovetailchannel. The first step acts to provide a first layer 182 of coatingmaterial to the exposed decorative surface and the outside bottom edges176 of the workpiece as seen in FIG. 21A to anchor the mesh 120. FIG.21B shown this first anchoring step acts to impregnate and anchor themesh 120 into the surface grooves 166 of the workpiece such that thecoating material infiltrates all of the grooves, cracks and creviceslocated in the surface of the workpiece and beneath the mesh. Once thecoated workpiece is driven through the coating chamber the first time itis then placed in an environmentally controlled chamber for 2-4 hours inorder that the first anchoring coating layer cures and shrinks onto andinto the decorative surface and outside bottom edges of the bottomportion of the workpiece. The workpiece is then run through theapparatus a second time with suitable changes made to theinterchangeable plates to apply a second top coat 184 or finishing coatto the workpiece. The second top coat 184 of coating material also helpsto provide a more durable finish to the workpiece. The finished coatedworkpiece is then again placed in the environmentally controlled chamberfor 2 to 4 hours for curing. The finished cured workpiece is then readyfor delivery and use. Alternatively, the coated workpiece 180 can be runthrough the apparatus again with suitably sized plates defining theinlet and die opening to apply an additional thin layer of coatingmaterial to the decorative surface of the workpiece.

[0099] The finished workpiece as seen in FIG. 22A has a first layer 182of coating material infiltrating and impregnating the mesh 120 into thesurface grooves of the workpiece and a second top layer 184 of coatingmaterial over the first layer. The outside bottom edges of the bottomportion of the workpiece 176 also has a very thin layer of coatingmaterial 183 that adds virtually no additional thickness over and abovethe thickness of the laminated mesh 120 such that the workpiece can bemounted via its bottom portion virtually flush against any surface.

[0100] Again, FIG. 22A illustrates the finished coated workpiece 180made by the two step process of the present invention. In the firststep, a first layer 182 of coating material is forced into the surfacegrooves of the workpiece to embed and bond the mesh 120 thereto (FIG.22B). In the second step, a second top layer 184 of coating material isprovided to add a finished coating to the workpiece which addsdurability to the finished coated product. Thus the finished coatedworkpiece 180 can withstand great forces without sustaining damage tothe finished hardened coated workpiece product. The second top layer ofcoating material is usually thinner than the first anchoring layer ofcoating material.

[0101]FIG. 23 shows a further embodiment of the finished workpiece asprovided by advancing the workpiece through the coating chamber of FIG.17A. In this embodiment, the outside bottom edges of the bottom portionof the workpiece has essentially no coating material and thus is readilymountable via its bottom portion flush against any surface.

[0102] The coated workpiece is cured under controlled conditions withinan environmental chamber after both the first and the second steps ofthe coating process. Specifically, the humidity, air temperature and thecirculation of air within the chamber is controlled to speed up thecuring of the coating material in a controlled manner. Thisenvironmentally controlled curing helps to shrink the coating materialinto the material of the workpiece and thus make the bond between thelaminated mesh, the coating material and the workpiece much stronger. Itis preferred to place the coated workpiece after both the first andsecond coating steps into the chamber for 2-4 hours until the coatingmaterial is dry. The environmental chamber is kept at about zero airhumidity to help speed up the drying process of the coating material.The temperature in the chamber can vary from 70° F. to 100° F. dependingon the temperature inside of the manufacturing plant. To providecirculating air fans are provided. Ideally, 2 sets of 4 fans are used inseries each set of fans generating 16,000 CFM for each fan. This isfound to provide satisfactory air circulation to speed up the curingprocess.

[0103] The apparatus encompassed by the embodiments of the invention mayadditionally incorporate a mesh applying station as shown in FIG. 24. Amesh applying station 58 is positioned in advance of the coatingchamber. Here, the workpiece is advanced in direction of arrow 59towards the coating chamber on a set of guide rollers 60. A pair ofopposing rotating wheels 36 are also positioned on either side of theworkpiece to minimize lateral horizontal movement of the workpiece as itis being advanced through the apparatus. A large mesh roll 62 issupported above the surface of the workpiece and unveils as theworkpiece is advanced. A roller 64 configured to mate with thedecorative surface is positioned biased against the top of the mesh asit is being applied to the surface of the workpiece to ensure that thetacky side of the mesh adheres completely to the decorative surface.Once covered in mesh, the workpiece is then moved and guided to thecoating portion of the apparatus.

[0104] In summary, the methods and the apparatus of the presentinvention provide an improvement over methods and other automatedcoating machinery of the prior art. Both the present methods andapparatus provide on a consistent basis, an even engineered smoothcoating with a controlled thickness to the entire exposed decorativesurface of a workpiece. In addition, the method also embodiesengineering a controlled thickness of coating material to desired bottomportions of the workpiece. This creates a finished workpiece that hassignificantly better physical properties than workpieces coated by priorart methods. The finished workpiece is more durable due to the fact thatthe method actually bonds the coating to the desired surfaces of theworkpiece such that the coating shrinks into all of the crevices andintricacies of the exposed surfaces of the workpiece. The finishedworkpiece is aesthetically pleasing and very durable.

[0105] The present invention avoids the problems of having air bubbles,cracks or an uneven thickness of coating material left on the coatedworkpiece. The method is simple, efficient, cost effective and worksconsistently in applying a plaster-like coating to the exposeddecorative surface of a workpiece such that several workpieces can becoated quickly and efficiently on a commercial scale for use in theconstruction industry.

[0106] Although preferred embodiments have been described herein indetail, it is understood by those skilled in the art that variations maybe made thereto without departing from the scope of the invention asdefined by the appended claims.

What is claimed is:
 1. An apparatus for applying a coating materialselected from the group consisting of cement based and polymeric basedmaterials to exposed surfaces of a preform workpiece having a decorativeexposed surface and a bottom portion, said apparatus comprising: meansfor mechanically advancing a workpiece along said apparatus along astraight horizontal axis over a non-continuous surface; means forengaging the bottom portion of a workpiece to constrain lateral andvertical movement as the workpiece passes along said apparatus; andmeans for applying a desired thickness of plaster-like coating materialto a decorative surface of an advancing workpiece.
 2. An apparatus asclaimed in claim 1, wherein said advancing means comprises an openplatform with means supporting a conveyor system therein.
 3. Anapparatus as claimed in claim 2, wherein said conveyor system comprisesa pair of adjacent conveyor belts for supporting and advancing aworkpiece through the apparatus.
 4. An apparatus as claimed in claim 3,wherein said conveyor belts additionally have a gripping means to helpdrive the workpiece with minimal lateral movement through the apparatuson said conveyor belts.
 5. An apparatus as claimed in claim 4, whereinsaid gripping means comprises a plurality of spikes protruding from thesurface of said conveyor belts, said spikes penetrating into the bottomportion of the workpiece to drive the workpiece with minimal lateralmovement through the apparatus.
 6. An apparatus as claimed in claim 1,wherein said engaging means comprises a rail extending vertically fromsaid non-continuous surface, said rail engaging with a correspondingchannel located within said bottom portion of the workpiece.
 7. Anapparatus as claimed in claim 1, wherein said apparatus additionallycomprises a restraining means for restraining vertical movement of aworkpiece as it is being advanced through said apparatus.
 8. Anapparatus as claimed in claim 7, wherein said restraining meanscomprises a tension wheel biased against the top surface of theworkpiece upstream of said coating means, said tension wheel rotatingalong the decorative surface of the workpiece as it is advanced throughthe apparatus.
 9. An apparatus as claimed in claim 1, wherein saidcoating means comprises a coating chamber having an inlet closelyconforming to the cross-sectional profile of a workpiece through whichthe workpiece is advanced, a plurality of conduits entering and openinginto the coating chamber through which a plaster like coating materialis fed from a reservoir such that the plaster like coating materialinfiltrates the irregular decorative exposed surface of the advancingworkpiece, and a die opening through which the coated workpiece exitsthe chamber, said die opening closely conforming to the cross sectionalprofile of the coated workpiece and wherein the size of the die openingdetermines the thickness of the plaster-like coating material allowed toremain on the coated decorative surface of the workpiece.
 10. Anapparatus as claimed in claim 9, wherein said conduits open into topportions and side portions of the coating chamber, such that coatingmaterial is fed onto the entire decorative exposed surface of theworkpiece as it is being advanced through the coating chamber.
 11. Anapparatus as claimed in claim 10, wherein said coating material is fedunder pressure.
 12. An apparatus as claimed in claim 9, wherein said dieopening conforms within approximately 2-4 mm at selected areas of thecross sectional profile of the coated workpiece.
 13. An apparatus asclaimed in claim 1, wherein said apparatus additionally,comprises ameans for laminating a mesh to the entire decorative exposed surface andto part of the bottom portion of the workpiece upstream of said coatingmeans.
 14. An apparatus as claimed in claim 14, wherein said meshlaminating means comprises; a pair of rotating wheels positionedunderneath the bottom flat portion of the workpiece to advance theworkpiece to the coating means; means for applying an adhesive mesh tothe workpiece as the workpiece is advancing; and means for adhering themesh to the workpiece.
 15. An apparatus as claimed in claim 1, whereinsaid advancing means comprises an open platform with a first meanssupporting a first conveyor system in said open platform positionedupstream of said coating means, said open platform also having a secondmeans supporting a second conveyor system in said open platform, saidsecond means positioned downstream of said coating means.
 16. Anapparatus as claimed in claim 15, wherein said first and second conveyorsystem each comprise a pair of adjacent conveyor belts having aplurality of spikes protruding from the surface of said conveyor belts,said spikes penetrating into the bottom portion of the workpiece todrive the workpiece through said apparatus.
 17. An apparatus as claimedin claim 1, wherein said engaging means comprises a rail extendingvertically from said non-continuous surface, said rail engaging with acorresponding channel located within said bottom portion of theworkpiece; said rail being positioned along the entire length of saidnon-continuous surface.
 18. An apparatus as claimed in claim 17, whereinsaid rail has an undercut and said corresponding channel is shaped tofit therein.
 19. An apparatus as claimed in claim 1 wherein said coatingmeans additionally comprises a means for defining an edge to applycoating material to a defined bottom outside edges of the bottom portionof said decorative workpiece.
 20. An apparatus as claimed in claim 19wherein said edge means comprises a pair of spaced apart dams slidinglyengaged on spaced apart rails located within a trough defining thebottom portion of said coating chamber, wherein said workpiece isadvanced through said coating chamber with said bottom edges of saidworkpiece substantially aligned with outside edges of said dams suchthat a controlled amount of coating material is provided on the outsidebottom edges of the bottom portion of said workpiece as the workpieceexits through the coating chamber.
 21. An apparatus as claimed in claim9, wherein said coating means has plates defining inlet and said dieopening, said plates being interchangeable in said coating means tofacilitate application of first and second coatings.
 22. A method forapplying a coating material to exposed surfaces of a preform workpiecehaving a decorative exposed surface and a bottom portion, said methodcomprising the steps of: continuously advancing said workpiece in astraight horizontal axis via engagement of said workpiece by its bottomportion to prevent lateral and vertical movement of said workpiece as itis being advanced; applying a plaster-like coating material to theexposed irregular decorative surface of the advanced workpiece; andadvancing the coated workpiece through a die opening closely conformingto the cross-sectional profile of the workpiece, wherein the crosssectional size of the die opening relative to the cross sectional sizeof the workpiece determines the thickness of the plaster-like coatingmaterial left remaining on the decorative surface of the coatedworkpiece.
 23. The method of claim 22, wherein said coating material isselected from the group consisting of cement based and polymeric basedmaterials.
 24. The method of claim 22, wherein said coating material isfed under pressure to the decorative exposed surface of the advancingworkpiece.
 25. The method of claim 22, wherein said method additionallycomprises; applying a thin layer of plaster-like coating material tosaid laminated mesh located on the outer bottom edges of the bottomportion of said advancing workpiece.
 26. The method of claim 22, whereinsaid coated workpiece is advanced through a second die opening to applya second layer of plaster-like coating material to said exposeddecorative surfaces of said workpiece.
 27. A preform workpiececomprising; an elongate body having an exposed decorative surface and asubstantially flat bottom portion; and means for facilitating theadherence of a coating material to the exposed decorative surface ofsaid workpiece, said facilitating means comprising a plurality of spacedapart surface openings orientated longitudinally along the body of theworkpiece into which the coating material adheres.
 28. The preformworkpiece of claim 27, wherein said openings comprise surface grooves.29. A coated workpiece comprising; a preformed workpiece of claim 27; amesh laminated to the exposed surface and partially about bottom outsideedges of bottom portion of said workpiece; and at least one layer of acoating material bonding said mesh to the exposed decorative surface andto bottom outside edges of the bottom portion of said workpiece, whereinthe coating material impregnates the mesh and anchors said mesh withinsaid surface grooves within said decorative exposed surface such thatthe mesh and coating material are firmly bonded to the decorativesurface of the workpiece.
 30. A coated workpiece of claim 29, wherein athin layer of coating material also impregnates and anchors the meshlocated about the bottom outside edges of the bottom portion of saidworkpiece.